Technical Field
The disclosure relates to an oil-based drilling fluid comprising jojoba oil, which is substantially free from diesel, mineral, and crude oil.
Description of the Related Art
The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present invention.
When drilling an oil well, a drilling fluid has to be used to transport the debris generated by drilling to the surface. The drilling fluid must also cool and lubricate the tool, maintain the wall of the borehole, exert a sufficient counter-pressure, and prevent damage to the formation (Hossain, M. E., Al-Majed, A. A., Fundamentals of Sustainable Drilling Engineering, ISBN 978-0-470-87817-0, John Wiley & Sons, Inc. Hoboken, N.J., and Scrivener Publishing LLC, Salem, Mass., USA, pp. 786, 2015—incorporated herein by reference in its entirety). Two types of drilling fluids are mainly used: water-based and oil-based fluids. Water-based fluids are more economical and ecologically acceptable than oil-based fluids. However, the latter have clear operational advantages, in particular when drilling under high pressure and high temperature conditions such as those in extremely deep wells. High pressure and high temperature wells often have pressures exceeding 69 MPa and temperatures higher than 150° C. The oil-based fluid is inert to the components of the geological formation, especially clay, thereby minimizing damage to the drill zone, and the fluid reduces friction better than water-based fluids.
Research in this field has gradually shifted from traditional oil-based fluids that are rich in diesel oil to oil-based fluids that usually contain plant oils and are therefore less noxious to the environment. However, the plant oils are not as thermally stable as diesel oil. In temperatures beyond 150° C., the environmentally-friendly plant oil-based fluids degrade, and can damage the reservoirs and reduce productivity in wells.
Safety and environmental factors are considered when choosing an oil for the drilling fluid. Products that have been used in the past may no longer be acceptable. As more environmental laws are enacted and new safety rules applied, the choice of the oil must also be re-evaluated. To meet the challenges of a changing environment, product knowledge and product testing become essential tools for selecting suitable oils for drilling fluid systems. Beginning in the 1990s, environmentally friendly drilling fluid systems have been developed that have low toxicity, easy degradation and little effect on environment. However, these fluid systems fail to be widely applied due to high costs or unsatisfactory application effects. There are also some newly developed drilling fluid systems which have complex synthetic process, failing to achieve industrialized manufacture. It is therefore necessary to develop a new environmentally friendly drilling fluid system which is easily synthesized, economical, and can protect the environment and oil reservoirs while satisfying the needs of drilling engineering. Several research groups have explored and reported low toxicity drilling fluids.
Bailey et al. (1986) examined viscosities of drilling fluids formulated with low toxicity mineral oil and diesel oil under different temperatures and pressures (T. Bailey, P. Bern, F. McEwan, 1986, Low Toxicity Oil Muds: A Knowledge of Downhole Rheological Behavior Assists Successful Field Application, SPE Drilling Engineering, 107-114—incorporated herein by reference in its entirety).
Yassin et al. (1991) carried out tests on palm oil derivatives as the oil in oil-based drilling fluids and the toxicity effect on plant and aquatic life (A. Yassin, A. Khamis, O. A. Mohamed, 1991, Formulation of an Environmentally Safe Oil Based Drilling Fluid, SPE Asia-Pacific Conference—incorporated herein by reference in its entirety). The oils used in this case were methyl esters of crude palm oil and methyl esters of fatty acids in distilled palm oil. Physio-chemical properties of these oils, such as flash point, pour point, aniline point, were characterized at various temperatures and pressures.
Sanchez et al. (1999) formulated drilling fluids from mineral oil, which has less than 0.1% aromatics, and palm oil, which does not have aromatics (G. Sanchez, N. Leon, M. Esclapes, I. Galindo, A. Martinez, J. Bruzual, I. Siegert, 1999, Environmentally Safe Oil Based Fluids for Drilling Activities, SPE/EPA Exploration and Production Environmental Conference—incorporated herein by reference in its entirety). The toxicity and biodegradability of mineral oil and palm oil-based drilling fluids were compared to those of a diesel oil-based drilling fluid. The results indicated that both drilling fluids containing mineral oil and palm oil are non-toxic while the diesel oil-based drilling fluid showed high levels of toxicity.
Dosunmu et al. (2010) developed an oil-based drilling fluid with palm oil and ground nut oil (A. Dosunmu, J. O. Ogunrinde, 2010, Development of Environmentally Friendly Oil Based Drilling fluid Using Palm Oil and Groundnut Oil, Nigeria Annual International Conference and Exhibition—incorporated herein by reference in its entirety). The fluid not only met the environmental standards, but also improved crop growth when discharged into farm lands.
Amanullah et al. (2010) proposed waste vegetable oil as an alternative to mineral oil and diesel oil in high performance drilling fluids for high pressure high temperature wells (M. Amanullah, H. H. Mohammed, 2010, The Recycling of Waste Vegetable Oil for Biodegradable and Environment Friendly OBM Formulation, The 2nd Saudi Meeting on Oil and Natural Gas Exploration and Production Technologies, KFUPM Campus, Dhahran, Saudi Arabia—incorporated herein by reference in its entirety). Large volumes of waste vegetable oil are generated annually worldwide. The drilling fluid with waste vegetable oil is not only eco-friendly, but also economical.
Apaleke et al. (2012) formulated a drilling fluid with canola oil as the base oil for an oil-based fluid, which is environmentally friendly, sustainable, and has zero level of toxicity (A. S. Apaleke, A. A. Al-Majed, M. E. Hossain, 2012, State of the Art and Future Trend of Drilling Fluid: An Experimental Study, SPE Latin America and Caribbean Petroleum Engineering Conference—incorporated herein by reference in its entirety). The developed canola oil system was found to be stable at room temperature and simulated downhole conditions. Moreover, the canola oil-based fluid system was formulated without a wetting agent which helped in reduction of the cost of formulation.
Fadiro et al. (2012) evaluated the environmental impact of three different oil-based fluids with base oils, diesel, jatropha oil, and canola oil (A. Fadairo, O. Falode, C. Ako, A. Adeyemi, A. Ameloko, 2012, Novel Formulation of Environmentally Friendly Oil Based Drilling fluid, New Technologies in the Oil and Gas Industry, 49-80—incorporated herein by reference in its entirety). The results obtained from laboratory tests indicated that jatropha oil has a low degree of toxicity and may be an environmentally viable replacement for the conventional and toxic diesel based fluid.
In view of the foregoing, the objective of the present invention is to provide an oil-based drilling fluid that contains jojoba oil, and which is substantially free from diesel, mineral, and crude oil.